Audio transducers such as loudspeakers frequently have difficulty reproducing bass (i.e. low audio frequency) audio frequencies.
It is known to utilise harmonics to generate apparent bass audio frequencies. This results from a psychoacoustic phenomenon where harmonics of low frequency sounds lead the listener to “hear” the fundamental low frequency even though the fundamental is not present.
Known apparatuses and methods vary signals over their dynamic range (i.e. volume or signal level) using apparatuses such as compressors or limiters.